Gasification of municipal solid waste in a downdraft gasifier: Analysis of tar formation

Abstract

In this study, municipal solid waste (MSW) from a dumpsite was converted into refuse derived fuel (RDF) and used as feedstock for an air-blown gasification process. The gasification process was conducted in a 10 kg.hr -1 downdraft gasifier at different air flow rates of 300, 350, 400, 450 and 550 NL.min1 at atmospheric pressure in order to investigate the quantity and quality of tar formed. It was shown that the increase in the air flow rate from 300 NL.min1 to 550 NL.min1 led to an increase in the oxidation temperature from 719°C to 870°C and an increase in the reduction temperature from 585°C to 750°C, respectively. Tar was reduced from 15 g.Nm3 to 4.7 g.Nm3 respectively. Heavy tar compounds (>C17) e.g. pyrene and phenathrene, decreased with the increase in the light tar compounds (<C10) e.g. naphthalene, indene and toluene; indicating the presence tar reduction through a tar cracking process.

Keywords

• tar formation
• tar reduction
• air blown gasification
• downdraft gasifier